Alternative to acetic acid for weak acid dyes?
  • This is more a technical curiosity than any sort of real issue, as I have never had any problem dyeing wool yarn with weak acid dyes using acetic acid... but can any alternative acids be used instead, or is there something about the dye chemistry which mandates the use of acetic acid?

    I've read that citric acid is being used by many as a non-odorous alternative to acetic acid for photographic stop baths in old-fashioned film and paper developing -- never mind that these aren't brought up to high temperatures and simmered for some time -- so it got me wondering.

    I'm thinking primarily of either citric acid or tartaric acid (the main acid in wine) as alternative weak acids because they're commonly found at homebrewing supply stores (and likely other places as well). They're also very inexpensive. Both are substantially stronger acids than acetic acid but are still considered weak acids, so less would be called for. Another advantage is they come in powdered form, just like the dyes themselves, and this mitigates the problem of storing a bulky and potentially spillable liquid like 28% acetic acid. Perhaps there are some other viable alternatives besides these two.

    What say your chemistry experts?
  • Citric acid is commonly used as a substitute for vinegar in dyeing.

    You can use citric acid in place of an equal volume of glacial acetic acid (which is 56% acetic acid in water), or eleven times the volume of distilled white vinegar (which is 5% acetic acid in water).

    For example, one tablespoon of citric acid, or 15 ml, is more-or-less equivalent to 15 ml of glacial acetic acid, or 165 ml of distilled white vinegar, which is eleven tablespoons. This is the amount you'd use to dye one pound of wool or other protein fiber with Jacquard Acid Dyes using the stovetop instructions.